Let-off mechanism for looms



March 10, 1931. w. s. WELLS 1,795,584

LET-OFF MECHANISM FOR LOOMS Original Filed Sept. 5, 192

INVENTOR, W'flZLa Patented Mar. 10, 1931 UNITED STATES PATENT OFFICE WILLIAM S. WELLS, OF LOS ANGELES, GALIFbBNIA, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO WONDER WEAVE, INC., BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS LET-OFF MECHANISM r012, Looms Original application filed September 5, 1828, Serial No. 304,060. Divided and this application filed July 81,

" 1929. Serial No. 882,508.

This invention relates to means for controlling the tension of yarn, thread, wire, strlps, 4

etc., while being drawn from a wound package thereof, as in the case of a warp in a loom. The principal object of the invention is to provide for perfect uniformity of tension even though the pull on the material varies for some cause, as for examplewhen the material, being the warp in a loom, is influenced by the shed-forming movements of the loom harness.

In the drawing,

Fig. 1 shows the mechanism of the invention in left side elevation, partly in section;

Fig.2isaplan;

Fig. 3 is a section on line 3-3, Fig. 1; and

Fig. 4 shows certain parts in right side elevation at the instant of tripping.

A support is formed by a plate 1 having its forward end portion 2 bent upward, a spindle 3 upstanding, from the plate and afiording a bearing, and an upright 4 (to be described in detail) also upstanding from the plate and arranged forward of the spindle. In the case where the warp in a loom is to be controlled, there will be a number of the supports and the 'parts they carry, one such assembly to a thread, and they may be all arranged on a creel or equivalent. I

On the spindle is revoluble a carrier wheel 5 affording around its center a number of uniformly spaced abutments 5a, as by said member being a ratchet-wheel asshown. On this member, and also revoluble on the spindle, is carried the bobbin or other core 6 of the package of wound material 7 .whose tension is to be controlled in the withdrawal thereof from the package. The carrier member and package in operation revolve as a unit, being here interlocked by the pin 56 on the former engaging a notch 6a in the core of the latter.

The upright 4 here takes the form of a strip of metal rigidly secured to the plate 1 and having both end portions upstanding and the extremity of one, 4a, bent off and abutting the side of the other, 4?). The portions in and i?) are connected by bearing pins 8 and 8, one above the other. The extremity of the portion 4?) is preferably bent oil, as at The rotation of the element formed by the interlocked carrier and package in the direction to unwind the latter when the yarn or thread is pulled upon is opposed by-means which is normally urged into rotation-opposing relation to said element but is movable out of said position, being adapted to maintain a bight or bend in and consequently preserve tension on the wound material extending from the package and on a pull being exerted on the material being ada ted to yield thereto to cause release of said e ement. v

A pawl or detent here in the form of a stiff wire is bent to provide two alined spirals 9a and a bend 9?) between them: This detent is essentially a lever, one arm of which is the bend 9b and the other one end 90 of the wire, the fulcrum'of the lever being the spirals 9a which have hearings on the pin 8. The arm 90 is normally held engaged with the notched periphery of the ratchet-wheel or carrier b a spiral spring 10 coiled around pin 8 an engaged at one end with upright 4 and at the other end with said arm.

The lever is here a stiff wire bent to provide.

two alined spirals 11a and a bend 116 between them. This is also essentially a lever, one arm of which is the bend 11b, another one end 110 of the wire, and a third may be afforded by the other end 11d of the wire, the fulcrum of the lever being the spirals 11a which have hearings on the pin 8'. In the position of rest of this tension lever it stands with the arm 11o bearing against the bent-off extremity of the portion 4a of the upright 4, the arm 11b rear-' wardly overlapping arm 9b of the detent or pawl and arm 11d projecting forwardly, the tension lever being held in this position by a spring 12 (and also in part by spring 10) which connects the last-named arm with some fixed point, as a screw 13 supported by a nut 14 hearing against the part of the upright 4.

The yarn 7 extends from the spool through a suitable guide- 15 on the upright, then in a bight or bend around a sheave 16 on the portion 2 of the support 1 and then in another bight or bend around a sheave 17 on the arm 110 of the tension lever.

Operation .In operation the tension lever occupies generally more or less the position shown by dotted lines in Fig. 1, being so held by the tendency of the pull on the yarn, taken with the resistance which 18 op posed to the rotation of the package-including element, to straighten the yarn or eliminate the bight. But under the -pull of the yarn the tension lever shifts to the right sufficiently to cause the pawl or detent to clear that tooth of the ratchet-wheel with which it happens to be engaged, immediately reactlng, so as to allow the pawl to engage a succeeding tooth of andthus again hold the ratchet-wheel, when the latter is thus freed; in other Words, the tension lever is vibratory in its said gen eral position, involving intermittent release of the package and consequent paying-out of yarn, with the latter however always under tension. Due to employing what in effect is an escapement mechanism of the class including a pawl and a wheel having teeth or abutments to be engaged by the pawl instead of one of that class (known in kindred tensioning yarn delivering apparatus heretofore proposed) including a brake and a brake-wheel and to the peculiar arrangement of the moving parts as shown I find that, in the control of slow-movingcoarse yarns in particular, such as asbestos yarns for instance, the tension maintained is perfectly uniform and that it is not affected by such extraneous influences as jars and vibrations.

The amount of tension may obviously be varied by adjusting the screw 13 to alter the resistance afforded by spring 12. In some instances the spring 12 may be substituted by another of different power.

The arm 90 is somewhat elastic wherefore, when as in the present example the escapement mechanism afforded by it and the wheel 5 is of the character in which the stopping of the wheel is accomplished by impact, such impacts are cushioned, which is in some cases ver desirable, as when the package is heavy an the force it represents consequently considerable.

This ap lication is a division of my application er. No. 304,060.

Having thus fully described my invention what I claim is:

1. In combination, a rotary wound package-including element, a movable detent normally urged into rotation-opposing engagement with said element but movable to release the same, ayarn guide,- and a yarn tension lever remote from said guide and normally urged from the detent but movable under the pull of the yarn to shift the detent clear of said element, said lever and guide normally maintaining the yarn in reverse bends.

2. In combination a support, a rotary 

